Subjects already implanted with a deep brain stimulation (DBS) system for therapy for essential tremor wear an Apple Watch and complete tremor assessment tasks detailed through the BrainRISE app four times a day for two weeks.

The smartwatch will collect data including accelerometry, heart rate, activity, move time, exercise time, stand time, steps, walking and running distance, heart rate variability, respiratory rate, six-minute walk, and flights climbed. During sleep, the smartwatch will collect daily nighttime physiologic data such as time in bed, average sleep time, sleep efficiency, wake after sleep onset, nocturnal heart rate, and nocturnal respiratory rate.

Acquisition of high-quality physiological signals from 50 subjects with movement disorders over the course of two weeks and up to thirty subjects over one day with 90% compliance rate as determined by the number of study tasks completed by participants.

Measured by wrist accelerometry, which tracks the acceleration of the patients' wrists and is reported in m/sec^2 on a scale where 1.0 = 9.8m/s^2.

Subject comfort, compliance, and convenience during the data collection as determined by a post-study assessment asking patients to rate their experience on a scale of 1-5 from hardest and most inconvenient to easiest and least inconvenient.